Field of the Invention
The present invention relates to an electrophotographic rotatable pressing member to be used in a fixing device configured to nip, convey, and heat a recording material, and a method of manufacturing the electrophotographic rotatable pressing member. The present invention also relates to a fixing device.
Description of the Related Art
In an electrophotographic image forming apparatus, a heat fixing device is used as a device configured to fix an unfixed toner image formed on a recording material onto the recording material. The heat fixing device includes a heating member and an electrophotographic rotatable pressing member arranged so as to be opposed to the heating member. The heat fixing device is configured to convey the recording material by rotation of the heating member and the electrophotographic rotatable pressing member while fixing a toner onto the recording material with heat from the heating member and a pressure caused by pressure contact between the heating member and the electrophotographic rotatable pressing member.
The electrophotographic rotatable pressing member includes a substrate and an elastic layer. The substrate gives stiffness sufficient for withstanding the pressure contact with the heating member. The elastic layer gives elasticity required for forming a nip portion. Further, a surface layer made of a fluorine resin for giving toner releasability may be formed on the elastic layer.
In International Publication No. WO2016/009527, there is described an invention which has an object to provide a pressurizing member capable of achieving, at a high level, both reduction in warm-up time and suppression of generation of creases extending in a circumferential direction. In this case, the warm-up time refers to a time period for raising the temperature of a nip portion to a temperature required for fixing a toner in order to reduce power consumption in a fixing device.
In International Publication No. WO2016/009527, there is described that the above-mentioned object can be achieved by the following configuration. That is, there is provided a pressurizing member including a substrate, an elastic layer formed on an outer side of the substrate, and a surface layer containing a fluorine resin formed on the elastic layer. The surface layer is fixed to the elastic layer under a state of being extended in a longitudinal direction, and the elastic layer has a hollow part ratio of from 20 vol % to 60 vol % or less. The pressurizing member has E(MD)/E(ND) being larger than 1.0, where E(ND) represents an elastic modulus of the elastic layer in a thickness direction, and E(MD) represents an elastic modulus of the elastic layer in a longitudinal direction. Further, there is disclosed that the above-mentioned physical properties are obtained by the elastic layer in which hollow parts are dispersed, the hollow parts being formed by evaporating water in a silicone rubber in which needle-shaped fillers are arranged in the longitudinal direction and water is dispersed.